Abstract: All oil and gas fields pay attention to how to solve the problem of leakage of oil and gas wells.The conventional cement slurry of cementing does not have the function of sealing.However,a net structure is easily to be formed in the leakage passageway due to the function of the fiber accumulation and bridging after adding inertia fiber into the conventional cement slurry of cementing.The conventional performance of the cement slurry does not change a lot.Therefore,the fiber cement slurry can block the leakage effectively during drilling and cementing.In addition,the limestone tenacity can be enhanced after being added the fiber,which guarantees the perforating job to carry on well.This article develops a type of fiber cement slurry system of sealing based on changing the volume and the length of the fiber.By applying the static simulation instrument for plugging cement,a lab simulation sealing test is conducted on the porous leakage with its bore diameter being 1 mm,2 mm,and 4 mm respectively and on the fractured leakage with its fracture radius being 1 mm and 2 mm.The result shows that the fiber cement slurry system exerts favorable effect on sealing the formations of porous leakage and fractured leakage.It has broad prospect as a kind of sealing agent of excellent performance.